1. Field of the Invention
This invention relates to gels prepared from novel anionic block copolymers of mono alkenyl arenes and conjugated dienes.
2. Background of the Art
The preparation of block copolymers of mono alkenyl arenes and conjugated dienes is well known. One of the first patents on linear ABA block copolymers made with styrene and butadiene is U.S. Pat. No. 3,149,182. These polymers in turn could be hydrogenated to form more stable block copolymers, such as those described in U.S. Pat. No. 3,595,942 and U.S. Pat. No. Re. 27,145. Such polymers are broadly termed Styrenic Block Copolymers or SBC's.
SBC's have a long history of use as adhesives, sealants and gels. A recent example of such a gel can be found in U.S. Pat. No. 5,879,694. With the increased use of oil gels, the need for improved properties (expressed in terms of higher tensile strength and higher elongation) exist. Such gels may also be used, for example, as a water proofing encapsulant/sealant for electronics and in wire and cable applications.
Now a novel anionic block copolymer based on mono alkenyl arene end blocks and controlled distribution mid blocks of mono alkenyl arenes and conjugated dienes has been discovered and is described in copending, commonly assigned U.S. patent application Ser. No. 60/355,210, entitled “NOVEL BLOCK COPOLYMERS AND METHOD FOR MAKING SAME”. Methods for making such polymers are described in detail in the above-mentioned patent application. Patentees have found that these new polymers will allow the preparation of improved oil gels. In particular, this invention comprises a new class of SBC's in which the polymer manufacturer can vary the compatibility characteristics of the rubber segment, resulting in improved oil gels.